The present invention relates to a method of manufacturing magnetic head elements (MR/GMR head elements), in which the width of ELG (Electric Lapping Guide) elements for monitoring the lapping process can be narrow so as to the increase number of magnetic head elements that can be manufactured.
Magnetic head elements used in magnetic disk drive units, and similar devices, are manufactured by forming magnetic layers, non-magnetic layers, and other layers on a wafer-shaped ceramic substrate. A plurality of sensing portions, each including a magnetic resistance effect head (a reading head) including an MR element an electromagnetic converting head (a recording head), and terminals (pads) connected thereto are formed on the substrate.
The magnetic head elements are formed by the steps of:
forming magnetic head element sections and terminals in the substrate; dividing the wafer into thin bar-shaped members 10 (see FIG. 6); and lapping a side face of the bar-shaped member (work piece). The bar-shaped member 10 is made by cutting the wafer, and tens of magnetic head element sections 12 are arranged therein.
The side face of the bar-shaped member 10 is lapped so as to adjust height (MR height) of the sensing portions including the layered MR elements, etc. to a prescribed height. If the height of the sensing portions is lower, the sensivity thereof can be higher. These days, the required MR height of the magnetic head element is 0.8 .mu.m.+-.0.2 .mu.m, and it will be 0.4 .mu.m.+-.0.05 .mu.m in the future.
As described above, the manufacturing accuracy of the sensing portions is extremely high, so lapping the bar-shaped member 10 a problem. In a conventional method, ELG elements are used when the bar-shaped member 10 is lapped.
In the bar-shaped member 10, each ELG element section 14 is adjacent to each magnetic head element section 12. Each ELG element 14 is used to control the amount of lapping of the adjacent magnetic head element section 12.
As described above, tens of the magnetic head element sections 12 are formed in the bar-shaped member 10, and high machining accuracy is required for each element section. Thus, the ELG element 14 is adjacent to the side of each magnetic head element section 12 so as to control the amount of lapping for each magnetic head element section 12 and to increase the machining accuracy.
In FIG. 6, reference numerals 16 stand for the element portions of the magnetic head element sections 12. Connecting pads 18a and 18b for reproducing, and connecting pads 20a and 20b for recording are formed on a surface of the bar-shaped member 10.
Pads 22a and 22b are formed on a surface of the ELG element 14.
FIG. 7 is a sectional view of the ELG element 14 taken along line A-A' in FIG. 6; FIG. 8 is a sectional view of the ELG element 14 taken along line a-a' in FIG. 6.
A non-magnetizable substrate, e.g., an Al.sub.2 O.sub.3 TiC substrate, is provided and a protecting layer 26 which is made of, for example, alumina, is formed on the substrate 25.
A lower shielding layer 27, which is made of sendust, is formed on the protecting layer 26. An alumina layer 28, which acts as a read-gap, is formed on the lower shielding layer 27. The MR element portions (sensing portions) 30, which are well known, are formed on the alumina layer 28.
Hard layers 31, for controlling magnetic domains, are made of CoCrPt, and they are respectively connected to both ends of each MR element portion 30. Lead layers 32, which are made of, for example, copper, are formed on the hard layers 31.
Terminal pillars 33, which are made of, for example, copper, are respectively formed at ends of the lead layers 32 as shown in FIG. 8.
The terminal pillars 33 are formed by plating holes in resist layers (not shown). The resist layers are removed.
An alumina layer 35, which acts as read-gaps and write-gaps, is formed on the alumina layer 28 and the lead layers 32.
An overcoating alumina layer 36 covers over the alumina layer 35 and the terminal pillars 33 to protect them.
The overcoating alumina layer 36 will be lapped until the terminal pillars 33 are exposed, then the monitor pads 22a and 22b, which are made of gold, will be formed on the exposed upper end faces of the terminal pillars 33.
The magnetic head element sections 12 are formed on the non-magnetizable substrate 25, by a known manner. In particular, the layer-structures of the sensing portions are almost the same as those of the ELG elements 14.
The connecting pads 18a and 18b are connected to the sensing part (not shown), which includes the MR element of the element portion 16 via the terminal pillars 38 (shown by dotted lines in FIG. 6). These pads 18a and 18b, as well as the terminal pillar 33 on the ELG element 14 side, inner lead layers 39 are made of, for example, copper.
The connecting pads 20a and 20b are connected to a thin coil layer (not shown) of the element portion 16 via the terminal pillars 41 (shown by dotted lines in FIG. 6). These pads are made of copper, for example, are as the terminal pillar 33 on the ELG element 14 side, and inner lead layers 41.
The bar-shaped member 10 is secured in a proper jig (not shown) and the side face P (see FIG. 6) is lapped. The MR element portions of the ELG elements 14 and the MR element portions of the magnetic head element sections 12 are simultaneously lapped. The jig has pressing means (not shown) capable of respectively pressing the magnetic head element sections 12 and the ELG elements 14 onto lapping means, and the lapping speed is adjusted so as to simultaneously complete the lapping work of all the magnetic head elements 12.
While performing the lapping work, the ELG elements 14 are connected to a monitor means (not shown) by the pads 22a and 22b, and the change in resistance of the MR element portions 30, which changes while lapping the MR element portions 30, is detected. The shape of the MR element portion of the magnetic head element section 12 and the shape of the MR element portion of the ELG element 14 should be same or very similar. By detecting the change in resistance of the MR element portions 30, the change of the resistance of the MR element portions of the magnetic head element sections 12 can be known, so that the lapping work is executed until the MR height of the MR element portions of the magnetic head element sections 12 reach a prescribed height.
By placing the ELG elements 14 adjacent to the magnetic head element sections 12 for monitoring purposes, the MR height can be controlled with higher accuracy.
After the lapping work, the bar-shaped member 10 is cut along the ELG elements 14 to divide the member 10 into a plurality of magnetic head element sections 12.
Since the ELG elements 14 are used for monitoring purposes only and are removed from the final products, width of the ELG elements 14 should be narrow so as to manufacture many magnetic head element sections 12 in one bar-shaped member 10.
FIG. 9 shows a state in which the overcoating alumina layer 36 is formed to cover the terminal pillars 33, 38 and 41 after the terminal pillars 33, 38 and 41, whose height are about 20-30 .mu.m, are formed. When the overcoating alumina layer 36 is formed by spattering, abnormal layers 37 (shown by dotted lines) are formed beside the terminal pillars 33, 38 and 41 due to step coverage thereof.
If separations between the terminal pillars 33, 38 and 41 are narrow, the abnormal layers 38 are high (see FIG. 10), and holes are opened when the terminal pillars are exposed by lapping. Note that, a line Q indicates a lapping face. To prevent forming the holes, the separations between the terminal pillars should be at least 100 .mu.m.
When the ELG elements 14 are cut, if the abnormal layers 37 are cut, chipping occurs because the abnormal layers are weak. To avoid chipping, the separation between the terminal pillar and the cutting line should be at least 55 .mu.m.
As described above, the width of the ELG element 14 is defined by spaces in which the terminal pillars are formed, so the minimum width is 300 .mu.m, and it cannot be narrower.